Device characteristics of double-gate MOSFETs with Si-dielectric interface model from first principle calculations

The first principle calculations based on density functional theory were performed to determine the band gap profiles and dielectric constants along the Si-Dielectric interface of CMOS device. The band gap changes almost linearly between Si and SiO₂ interfaces with transition depth of 5 Å. The calculated dielectric constants change almost abruptly at Si/SiO₂ interface. Thus-obtained band gap profile and dielectric constants were used in electron transport simulation of ultra-thin-body n-type double-gate MOSFETs. The self-consistent potential profile in the channel and gate leakage current were calculated accurately using the non-equilibrium Green´s function approach. The effect of the band gap transition across the Si/SiO₂ interface on the device performance is investigated.